Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

Rembauville, Mathieu; Salter, Ian; Leblond, Nathalie; Guéneuguès, Audrey; Blain, S.

doi:10.5194/bg-12-3153-2015

Cited by 31 publications

(41 citation statements)

References 128 publications

(146 reference statements)

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“…The carrousel comprised 12 sampling cups (250 mL) containing 5% formalin hypersaline solution buffered with sodium tetraborate (pH¼8). A detailed description of the sample processing and particulate organic carbon (POC) analyses are provided in Rembauville et al (2015b). Briefly, swimmers (zooplanktonic organisms actively entering the trap) were manually removed, samples were freeze-dried and the carbonate fraction was dissolved by the addition of acid before the organic carbon content was measured with a CHN analyzer.…”

Section: Sediment Trap Deployment and Environmental Datamentioning

confidence: 99%

“…At the A3 station, the circulation is weak (o3 cm s À 1 ) and primarily tidal-driven (Park et al, 2008). Physical data acquired during the sediment trap deployment suggest the record was not subject to major hydrodynamic biases (Rembauville et al, 2015b), allowing a detailed and quantitative discussion of the export fluxes.…”

Section: Sediment Trap Deployment and Environmental Datamentioning

confidence: 99%

“…For the fine fractions (20-63 mm and o20 mm) Ca analyses, the original 1/8 split samples (Rembauville et al, 2015b) were further split into 1/80 aliquots with a rotary wet-splitter (McLane WSD-10) using purified water (Elix by Millipore purification system) buffered with ammonia as a rinse solution. Coccoliths in sinking particles captured in sediment trap samples may be contained in faecal pellets and/or phytoplankton aggregates.…”

Section: Calcium Analyses In the Bulk And Fine Fractionsmentioning

confidence: 99%

“…Only one empty shell of pteropod (Limacina helicina) was found in the samples and therefore pteropod's contribution to the passive carbonate flux was considered negligible. However, numerous pteropods were found as swimmers (distinguished by well preserved organic material) actively entering the trap in late summer (Rembauville et al, 2015b). Those shells were withdrawn from the samples as they were considered not to contribute to the passive flux.…”

Section: Foraminifer Carbonate Flux Estimationmentioning

confidence: 99%

“…The annual POC export (98.2 mmol m À 2 yr À 1 , Rembauville et al, 2015b) and the annual PIC export (6.6 mmol m À 2 yr À 1 ) at station A3 allow us to estimate the strength of the carbonate counter pump: the reduction of the CO 2 drawdown by the biological pump due to the CO 2 production during the calcification process in the mixed layer (Frankignoulle et al, 1994;Zeebe, 2012;Salter et al, 2014). As the trap depth (289 m) was close to the winter mixed layer depth (220 m in this region of the Southern Ocean (Park et al, 1998;de Boyer Montégut et al, 2004), POC fluxes were not corrected for attenuation with depth.…”

Section: Southern Ocean Carbonate Counter Pump Affected By Different mentioning

confidence: 99%

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Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Rembauville

Meilland

Ziveri

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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a b s t r a c tWe report the contribution of planktic foraminifers and coccoliths to the particulate inorganic carbon (PIC) export fluxes collected over an annual cycle (October 2011/September 2012) on the central Kerguelen Plateau in the Antarctic Zone (AAZ) south of the Polar Front (PF). The seasonality of PIC flux was decoupled from surface chlorophyll a concentration and particulate organic carbon (POC) fluxes and was characterized by a late summer (February) maximum. This peak was concomitant with the highest satellite-derived sea surface PIC and corresponded to a Emiliania huxleyi coccoliths export event that accounted for 85% of the annual PIC export. The foraminifer contribution to the annual PIC flux was much lower (15%) and dominated by Turborotalita quinqueloba and Neogloboquadrina pachyderma. Foraminifer export fluxes were closely related to the surface chlorophyll a concentration, suggesting food availability as an important factor regulating the foraminifer's biomass. We compared size-normalized test weight (SNW) of the foraminifers with previously published SNW from the Crozet Islands using the same methodology and found no significant difference in SNW between sites for a given species. However, the SNW was significantly species-specific with a threefold increase from T. quinqueloba to Globigerina bulloides. The annual PIC:POC molar ratio of 0.07 was close to the mean ratio for the global ocean and lead to a low carbonate counter pump effect ( $ 5%) compared to a previous study north of the PF (6-32%). We suggest that lowers counter pump effect south of the PF despite similar productivity levels is due to a dominance of coccoliths in the PIC fluxes and a difference in the foraminifers species assemblage with a predominance of polar species with lower SNW.

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Section: Sediment Trap Deployment and Environmental Datamentioning

confidence: 99%

Section: Sediment Trap Deployment and Environmental Datamentioning

confidence: 99%

Section: Calcium Analyses In the Bulk And Fine Fractionsmentioning

confidence: 99%

Section: Foraminifer Carbonate Flux Estimationmentioning

confidence: 99%

Section: Southern Ocean Carbonate Counter Pump Affected By Different mentioning

confidence: 99%

See 3 more Smart Citations

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Rembauville

Meilland

Ziveri

et al. 2016

Deep Sea Research Part I: Oceanographic Research Papers

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The role of particle associated microbes in remineralization of fecal pellets in the upper mesopelagic of the Scotia Sea, Antarctica

Belcher

Iversen

Manno

et al. 2016

Limnology & Oceanography

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Fecal pellets (FP) are a key component of the biological carbon pump, as they can, under some circumstances, efficiently transfer carbon to depth. Like other forms of particulate organic carbon (POC), they can be remineralized in the ocean interior (particularly in the upper 200 m), or alternatively they can be preserved in the sediments. The controls on the attenuation of FP flux with depth are not fully understood, in particular, the relative contributions of zooplankton fragmentation and microbial/zooplankton respiration to FP loss. Collection of sinking particles using Marine Snow Catchers at three ecologically contrasting sites in the Scotia Sea, Antarctica, revealed large differences in POC flux composition (5-96% FP) and flux attenuation despite similar temperatures. To determine the importance of microbial respiration on FP loss in the upper mesopelagic, we made the first ever measurements of small scale oxygen gradients through the boundary layer at the interface of krill FP collected from the Scotia Sea. Estimated carbon-specific respiration rates of microbes within FP (0.010-0.065 d 21 ) were too low to account for the observed large decreases in FP flux over the upper 200 m. Therefore, the observed rapid declines in downward FP flux in the upper mesopelagic are more likely to be caused by zooplankton, through coprophagy, coprorhexy, and coprochaly. Microbial respiration is likely to be more important in regions of higher temperatures, and at times of the year, or in depths of the ocean, where zooplankton abundances are low and therefore grazing and fragmentation processes are reduced.

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Particulate matter stoichiometry driven by microplankton community structure in summer in the Indian sector of the Southern Ocean

Rembauville

Blain

Caparros

et al. 2016

Limnology & Oceanography

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Microplankton community structure and particulate matter stoichiometry were investigated in a late summer survey across the Subantarctic and Polar Front in the Indian sector of the Southern Ocean. Microplankton community structure exerted a first order control on PON:POP stoichiometry with diatom‐dominated samples exhibiting much lower ratios (4–6) than dinoflagellate and ciliate‐dominated samples (10–21). A significant fraction of the total chlorophyll a (30–70%) was located beneath the euphotic zone and mixed layer and sub‐surface chlorophyll features were associated to transition layers. Although microplankton community structure and biomass was similar between mixed and transition layers, the latter was characterized by elevated Chl:POC ratios indicating photoacclimation of mixed layer communities. Empty diatom frustules, in particular of Fragilariopsis kerguelensis and Pseudo‐nitzschia, were found to accumulate in the Antarctic Zone transition layer and were associated to elevated BSi:POC ratios. Furthermore, high Si(OH)4 diffusive fluxes (>1 mmol m2 d−1) into the transition layer appeared likely to sustain silicification. We suggest transition layers as key areas of C and Si decoupling through (1) physiological constraints on carbon and silicon fixation (2) as active foraging sites for grazers that preferentially remineralize carbon. On the Kerguelen Plateau, the dominant contribution of Chaetoceros Hyalochaete resting spores to microplankton biomass resulted in a three‐fold enhancement of POC concentration at 250 m, compared to other stations. These findings further highlight the importance of diatom resting spores as a significant vector of carbon export through the intense remineralization horizons characteristing Southern Ocean ecosystems.

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Export fluxes in a naturally iron-fertilized area of the Southern Ocean – Part 1: Seasonal dynamics of particulate organic carbon export from a moored sediment trap

Cited by 31 publications

References 128 publications

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

Planktic foraminifer and coccolith contribution to carbonate export fluxes over the central Kerguelen Plateau

The role of particle associated microbes in remineralization of fecal pellets in the upper mesopelagic of the Scotia Sea, Antarctica

Particulate matter stoichiometry driven by microplankton community structure in summer in the Indian sector of the Southern Ocean

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